impossible in WordNet English dictionary

1. something that cannot be done
   "his assignment verged on the impossible"
   impossible 
   

1. not capable of occurring or being accomplished or dealt with
   "an impossible dream"; "an impossible situation"
   impossible 
   
2. used of persons or their behavior
   "impossible behavior"; "insufferable insolence"
   impossible  insufferable  unacceptable  unsufferable 
   
3. totally unlikely
   impossible  inconceivable  out of the question  unimaginable